Means for protecting x-ray tubes



Dec. 15 1925.

H. D. GARRETSON MEANS FOR PROTECTING X-RAY TUBES Filed Nov. 14. 1922 Patented Dec. 15, 1925.

UNITED STATES HARRY D. GARRETSON, OF NEW YORK, N. Y.

MEANS FOR PROTECTING X-RAY TUBES.

Application filed November 14, 1922.

To all whom it may concern:

Be it known that I, HARRY D. GARRErsoN, a citizen of the United States, and a resident of the city, county, and State of New York, have invented a new and useful Improvement in Means for Protecting X-Ray Tubes, of which the following is a specification.

It is well known that when an inverse current is passed through a hot X-ray tube there is a great probability that the tube will be ruined. The object of my invention is to render impossible the passage of such a current. This and other objects are accomplished by my invention, one embodiment of which is hereinafter more particularly set forth.

For a more detailed description of my 1nvention, reference is to be had to the accompanying drawings, forming a part hereof, in which is shown a diagrammatic vlew of one embodiment of my invention.

It is assumed for the purposes of this illustration, that the bus bars are 1 and 2 and that these are supplied with electricity from any suitable source. These bars are connected with conductors 3 and 4 by means of a switch 5 which is built and operates as usual. The wires 3 and 4 run to a pole changing switch 6 and are also connected to wires 7 and 8 which run to a four pole synchronous motor 9 which has a rotating armature 10 without a winding and with a soft iron core. This motor 9 also has field coils 11 which are connected to the wires 7 and 8, as indicated, or in any other suitable manner.

The wire 7 and wire 12 connect to the armature 13 of a polarized relay 14 and this polarized relay has amagnet with a north pole 15 and a south pole 16, or the reverse, each of which is surrounded by a suitable solenoid and these solenoids are connected, as indicated, if one wire 17 runs to the solenoid on the pole 16 and another wire 18 runs to the other solenoid. The armature 63 of the synchronous motor 9 is extended so as to receive a pole changing switch 19 which is fixed thereon and provided with two insulated bars or sections and two conducting bars or sections. The conducting bars or sections are cross connected so that a bruslr 20 whlch 1s connected to the wire 17 may form and connect through the switch 19 to a brush 21 which is connected to a wire 22 which runs to a regulator 23 of a step-up tran former andtlusregu1ator placed Serial No. 600,792.

on the low tension side, the low tension coil being indicated by the character 25 and the high tension coil by the character 26.

This low tension coil has a connection through a wire 27 with a terminal 28 in the magnetic switch 29 which has a core 30 which may be drawn into a solenoid 31 so as to cause a bar 32 of this switch to connect the contact 28 with the correspondin contact 33 which has a conductor 34 whic connects it to the pole changer 6. An 0pposite pole of this pole changer 6 is connected by a conductor 35 with the'regulator 23, above mentioned.

This conductor 34 also has a connection with the wire 18 above mentioned.

The wire 8 has a conductor 36 which runs to an exposure switch 37 which may be a single jaw switch of any suitable kind, and this switch has a conductor 38 which runs to the magnet 31 and the other end of this magnet is connected by a wire 39 with a fixed contact 40 of the polarized relay 14. Another contact 41 of this polarized relay has a conductor 42 which runs to a pilot light 43, which is preferably red, and this light has a conductor 44 which runs to the wire 8.

The armature 13 of the polarized relay 14 may connect either of the contacts 40 or .41 and it is so arranged and designed that it will be controlled by a spring 45 so as to be held in contact with the contact 41 unless the magnets 15 and 16 are properly energized so as to draw this armature 13 against the tension of this spring, in which event this armature will engage with the contact 40. When this-armature engages the contact 41 a circuit is established between the wires 7 and 8 through the lamp 43 which. will glow. This means that the polarized relay has a current passing through its magnets 15 and 16 which is in opposition to them. If the light does not glow, the armature 13 will overcome the tension of the spring 40 because the mag netic action of the coils 16 and 15 cooperates with the magnetism of the permanent magnet and this occurs when the rotary switch 19 has its brushes 20 and 21 connect atthe time of the proper phase relation which will be described below. i

The secondary 26 of the step-up transformer 24 has two wires 46 and 47 which run to the distributing wires 48 and 49. The wire 48 has balls 50 and 51, one ball at each end, and the 49' has correspondingbells 52 and 53. These balls are opposed to corresponding balls 54, 55, 56 and 57, the balls 54 and 56 being at the end of a positive conductor 58 and the balls 57 and 55 being on a negative conductor 59. The conductors 58 and 59 are connected by an X-ray'tube 60 in the conventional manner. This tube may be any sort of a tube. If it be a hot cathode tube, suitable arrangements must be made, the conventional kind, for heating the hot cathode. To simplify the explanation, the tube is shown as one of the gas type.

Diagonally opposed balls may be connected by means of cross conductors 61 and 62 which are fixedly mounted in a rotating shaft 63 on which is also mounted the armature 10 of the motor-9 and the rotary interrupting switch 19 so that the arms 61, 62, ar-- mature 10 and switch 19 will always function in the samephase relation.

It is apparent from the foregoing that the conductor 61 will at one time connect the ball 52 with the ball 56 and at another time connect the ball 50 with the ball 54 and the conductor 62 will connect the ball 51 with the ball 55 and the ball 53 with the ball 57.

lVhile the parts 50 to 57 inclusive are called balls this is merely for the convenience of description. If desired, these parts need not be balls at all; they may be segmental or other conductors, as is obvious.

Operation.

In view of the foregoing, the operation of my improved device will be readily understood. If the switch 5 be closed and current turned on to the system above described, the motor 9 will at once begin to function and its armature 10 to rotate and thereby drive the shaft 63. lVhen so driven, the conductors 61 and 62 will have the proper phase relation to the balls 50 to 57 inclusive or they will not. Let it be assumed that this phase relation is not correct or that the brushes and 21 are connected on the wrong phase. This may occur in the midst of the normal operation of the apparatus through a retarding of phase or overload or otherwise at other points of the circuit, as is well understood. When this occurs, a circuit is complete through these brushes in opposition to the fixed magnet of the polarized relay 14 and this opposition makes this magnet so weak that it connot draw its armature 13. When this occurs a circuit is closed through the contact 41 and the light 43 illuminates. This indicates to the operator that the proper phase relation does not obtain. He thereupon throws his pole changer 6 and thereby reverses the polarity of the current passing through the transformer 24. As soon as this is done the brushes 20 and 21 are in proper phase relation so that a current passing through the conductors l7 and 22 will reinforce the fixed magnet of the polarized relay 14 and thereby make it strong enough to draw the armature 13 and remove this armature from the contact 41 so that the light 43 is extinguished. When the operator notices this, he closes the switch 87 and then the magnetic switch 29 is closed and the prin'iary 25 of the step-up transformer 24 is energized and then the secondary 26 is energized and the rectifying switch connected thereto will function so as to cause the tube 60 to generate X-rays. It is impossible for the magnetic switch 29 to close under any other circumstances because this switch cannot be closed unless the armature 18 rests on the contact and it cannot do this unless the proper phase relation established, as above set forth. From this it follows that it is impossible to send an inverse current through the tube with the apparatus made, as above stated.

While I have shown and described one embodiment of my invention, it is obvious that it is not restricted thereto but that it is broad enough to cover all structures that come within the scope of the annexed claims.

Having thus described my invention, what I claim is:

1. In a system of the class described, an X-ray tube, a rectifying switch, means for passing a high tension current to said tube through said switch, a synchronous motor driving switch, a polarized relay connected to said synchronous motor and means con trolled by said polarized relay for prevent- W ing any inverse current to flow to the X-ray tube.

2. In a system of the class described, an X-ray tube, a rectifying switch connected to said tube, a synchronous motor for driving 1 5 said switch, a transformer having a secondary connected to said rectifying switch and a primary connected to a source of power through a circuit. breaking switch and means connecting said circuit breaking switch and 110 the synchronous motor so that all current will be out oif from the primary of said transformer whenever a current in the proper direction does not flow through said tube.

3. In a system of the class described, an X-ray tube, a rectifying switch, a synchronous motor for driving the rectifying switch, a rotary switch also driven by the synchronous motor, a step-up transformer having a I20 secondary connected to the synchronous switch and a primary to a source of power,

a circuit breaking switch in the primary circuit with a solenoid controlling the same, a glow light, a polarized relay with its arma- 125 ture connected so that either the solenoid may be energized or the glow light, but not both at once, and connections between the rotary switch and the source of power and the solenoid and glow lamp and the source 130 of power so that when the X-ray tube is functioning properly and is energized, the solenoid will be energized and the glow light will not glow and when an inverse current starts to flow though the tube, the polarized relay will function so as to shift its armature and permit the glow light to be energized HARRY D. GARRETSON. 

